Background: Motion sickness (MS) is a common syndrome characterized by autonomic and behavioral symptoms, such as nausea and dizziness, resulting from exposure to motion stimuli. Its pathophysiology is closely linked to sensory conflict and postural instability theories. While previous studies suggest that postural control, proprioception, and reaction times are affected in individuals susceptible to MS, there is a lack of comprehensive, comparative research evaluating all these parameters concurrently within the same cohort using standardized methods. Objective: This study aims to systematically measure balance, proprioceptive sensitivity, coordination, and reaction time parameters, and quantitatively analyze their relationship with motion sickness severity. Methodology: In this prospective, cross-sectional study, at least 41 participants aged 18-40 with motion sickness will be recruited. Participants will undergo motion sickness susceptibility and severity grading using the Motion Sickness Susceptibility Questionnaire Short Form (MSSQ-SF) and the Graybiel Scale. Objective assessments will include static and dynamic balance testing (ProKin®), knee joint position sense (Clinometer app), manual dexterity and dynamic balance coordination (Nine-Hole Peg Test, Tandem Walk, Romberg Test), and upper/lower extremity reaction time measurements (BlazePod system).